1. Technical Field
This invention relates generally to battery chargers, and more specifically to an electrically-conductive metal contact for delivering power from a power source to a rechargeable battery.
2. Background Art
Battery chargers deliver power from a power source to a rechargeable battery cell. The popular way to connect the charger to the battery is by way of an electrically-conductive metal contact. Referring now to FIG. 1, illustrated therein is a typical prior art charger 100, as disclosed in U.S. Pat. No. D432,983. The charger 100, shown here in a top, plan view, includes a pocket 101 that has a set of spring-loaded electrical contacts 102. The contacts 102 project upward from the bottom of the pocket 101. When a portable electronic device or rechargeable battery is placed in the pocket, gravity pulls the device or battery against the contacts, thereby ensuring a proper electrical connection.
While this system works well for some portable electronic devices, it does not work well for all of them. For example, the large, industrial radios used by policemen and firemen generally do not have electrical contacts on their bases. The contacts are located on the side of the battery instead. Additionally, these batteries are often too large to lay on their sides to take advantage of the gravity-based system shown in FIG. 1.
To complicate matters further, these batteries often have recessed contacts, i.e. the contacts are sunken below the outer surface of the battery. The amount of recess varies from battery to battery. As a result of these issues, it is desirable to have a charger capable of charging a battery in a vertical position while accommodating battery contacts of varying recess depths.
One such solution is shown in FIG. 2. In FIG. 2, a battery charger 200 is shown with an electrical contact 202 disposed on the side of the pocket 206. To accommodate battery contacts of varying recess depths, the contact 202 has been spring loaded by way of a coiled spring 203 placed between the contact 202 and a mechanical stop 204. In this manner, the contact 202 is capable of protruding through the pocket wall 206 in varying amounts.
The problem with this prior art solution is that if the contact 202 protrudes far enough through the pocket wall 206 to make a sufficient electrical connection with a deeply recessed contact on a battery, the contact 202 may cause interference with a battery 201 when it is inserted into the charger 202. As shown in FIG. 2, the contact 202 interferes with battery insertion at point 205. Repeated interference with the contact 202 may cause the contact, and thus the charger, to fail.
There is thus a need for an improved contact system that accommodates sidewall connection to battery contacts of varying recess depths.